IL112706A - Process for the preparation of hydroxyphthalic acids by low-temperature hydrolysis of bromophthalic acids - Google Patents

Description

Ref: 2885/93 112706/2 PROCESS FOR THE PREPARATION OF HYDROXYPHTHALIC ACIDS BY LOW-TEMPERATURE HYDROLYSIS OF BROMOPHTHALIC ACIDS - - Field of the Invention The present invention relates to the preparation of hydroxyphthalic acid and anhydride.

More particularly, the invention relates to the preparation of 4-hydroxyphthalic acid (4-HPA) and a mixture of 3- and 4-hydroxyphthalic acids, by hydrolysis of the 4-bromophthalic acid (4-BPA) or a mixture of 3- and 4- bromophthalic acids, in aqueous alkaline solutions.

Background of the Invention 4-HPA is used as a starting material for a variety of products, such as drugs, agrochemicals and polymers (S. Sasaki et al., JP 63,122,668, S. Sasaki et al., JP 62 99,371 and S. Sasaki et al., EP 195,402).

The preparation of 4-HPA by the hydrolysis of 4-sulphophthalic acid and 4-halophtha c acid was published in 1959 (W. Muller et al., DE 1,065,425). The yields reported in this patent are remarkably high (>93%); however, the ensuing literature reveals disparities in the yields, due to extensive decarboxylation of the phthalic moiety. This procedure - with lower yields - was reported by K. Nagaoka et al., JP 61,140,578, and K. Nagaoka et al., JP 61,140,541. Furthermore, all these references fail to disclose a specific example based on hydrolysis of 4-BPA, and do not suggest a solution to the decarboxylation problem, that is responsible for the low yield of the hydrolysis process.

The fact that hydroxyphthalic acid can undergo a decarboxylation reaction has already been exploited to produce 3-hydroxybenzoic acid (K.C. Willis et al, US 3,099,686, R. Putthast et al., DE 3,017,983 and US 4,354,038).

It is an object of the present invention to provide simple and economic processes for the preparation of 4- hydroxyphthalic acid or a mixture of 3- and 4-hydroxyphthalic acids, and hydroxyphthalic anhydride.

It is another object of the present invention to provide a process in which 4-hydroxyphthalic acid or a mixture of 3- and 4-hydroxyphthalic acids or hydroxyphthalic anhydride are obtained in high yield and with high purity. , It is a further object of the present invention to provide a process for preparation of 4- hydroxyphthalic acid or a mixture of 3- and 4-hydroxyphthalic acids wherein no substantial decarboxylation occurs.

Summary of the Invention According to the invention, 4- hydroxyphthalic acid or a mixture of 3- and 4-hydroxyphthalic acids and hydroxyphthalic anhydride are prepared by a process that comprises of hydrolyzing 4-bromophthalic acid or a mixture of 3-and 4-bromophthalic acids, respectively, in the presence of a copper compound catalyst in an aqueous alkaline solution at a temperature between 100° and 160°C. Hydroxyphthahc anhydride can be prepared by dehydration of the corresponding acid by any known method, as described in JP 61,140,578 and JP ■ 61,140,541.

Detailed Description of Preferred Embodiments The starting materials that could be used, in principle, for the preparation of 4-hydroxyphthalic acid or a mixture of of 3- and 4-hydroxyphthalic acids are the corresponding sulpho-, fluoro-, chloro-, bromo- and iodophthahc acids. The fluoro-and iodophthahc acids are relatively expensive and are of limited industrial value for the production of HPA, although the can be hydrolyzed. The sulpho- and chloro-phthahc acids can be hydrolyzed at a rate that is of industrial consideration only at high temperatures at which a substantial amount of the product is decarboxylated. The addition of any catalyst to the chloro-phthalic acids leads to no significant improvement, so there is no advantage in the use of chloro-phthahc acids, especially in light of the fact that the preparation of the separate isomers of said acids is technically difficult (low specificity of the chlorination of phthahc acid).

In contrast, 4-bromophthalic acid and a mixture of 3- and 4-bromophthalic acids, can be produced in an economic manner by the bromination of disodium phthalate, as described in US 2,394,268, and can be hydrolyzed in the presence of a suitable catalyst and base, at the relatively low temperature that is necessary to avoid the decarboxylation side reaction. The respective acid salts, mono-alkali and/or dialkali phthalates are all equally suitable for the process, provided that the preferred molar ratio of base to substrate is maintained.

The prior art discloses hydrolysis processes that occur readily at high temperatures, usually above 200°C. Lower temperatures were considered impractical because of the low hydrolysis rate, hence the advantage of operatin at relatively low pressures associated with low reaction temperatures cannot be exploited. In the process of the invention this limitation has been removed, and the process may be conducted at temperatures lower then 160°C, preferabl at 110°-140°C. The consequence of such a decrease in the temperature range is a reduction in the decarboxylation, leading to improved yields. This principal improvement of the present invention by the use of the bromophthalic acid, is completely unexpected and is, of course, of great importance.

The copper compound catalyst preferred is a catalyst of the formula Cu(n)R(m), in which: R is -O , -OH or the anion of an inorganic or organic acid; n is 1 or 2; and m is 0, 1 or 2.

Examples of copper compound catalysts of the invention are Cu, CuCl, CuO, CuBr2, CuCl2, CuBr, Cu2O, Cu(OH)2, CUSO4, Cu(OAc)2, and other known copper salts of organic and inorganic acids. One such copper compound catalyst can be used in a reaction step, or mixtures of two or more of these compounds can be employed together. The total amount of copper compound catalysts in the reaction is between 0.01% to 10% by mole, preferably between 1 to 5% b mole with respect to the starting material. Table III summarizes the effect of varying the ratio of catalyst to substrat, while example 16 describes the effect of the use of various catalysts. At the end of the hydrolysis step, the copper compound catalyst can be filtered off and reused in a subsequent reaction.

The alkali can be selected from the hydroxides, oxides and carbonates of sodium and potassium and mixtures thereof. The corresponding compounds of alkaline earth metals can also be used. The content of the alkalis in the aqueous solution is between 5 and 10 times the equivalent of the halogen atom in the starting material, preferably between 5-7, calculated on a mole basis. Examples 4 and 7^10, summarized in Table II, illustrate the effect of varying the base to substrate ratio.

All of the above, as well as other characteristics and advantages of the invention, will be better understood through the following illustrative and non-limitative examples of preferred embodiments.

Example 1 Into a one liter autoclave a mixture of 4-BPA (196 g, 0.8 mole), aqueous 7N NaOH (571 ml., 4 moles) and CuCl (1.0 g, 0.01 mole) was placed.

The autoclave was sealed and heated to 150°C. Full conversion was achieved after 0.7 hour. The autoclave was cooled to room temperature, opened, and the reaction mixture was filtered to remove the catalyst.

The filtrate was placed into a four-necked flask equipped with a stirrer, a condenser, a dropping funnel and a thermometer, and acidified to pH 1 with 32% HC1 (350 ml) at 60-80°C until full dissolution was obtained. The mixture was then cooled by stirring, and extracted with ethyl ether. GC analysis of the ether solution indicated 4-HPA of 96.5% purity. After removal of the solvent 140.5g 4-HPA were obtained.

Examples 2 - 6 Temperature effect on the hydrolysis of 4-bromophthalic acid in the presence of a copper catalyst at a constant base/4-BPA ratio of 5:1 Example 1 was repeated under various conditions (see Table I): Table I % = molar percent 4-BPA = 4-bromophthalic acid 4-HPA = 4-hydroxyphthalic acid 3-HBA = 3-hydroxybenzoic acid PA = phthalic acid N.D = no data detected Examples 7-10 The effect of the base/4-bromophthalic acid ratio at constant temperature and catalyst Example 1 was repeated at 140°C for one hour using various amounts of base as detailed in Table II: Table II Example NaOH/ Conversion 4-BPA 4-HPA 3-HBA PA No. 4-BPA % (Br) % % % % molar ratio 7 2 <10 90.0 <10.0 0.2 0.3 8 . 3 68 31.3 22.7 40.5 4.9 9 4 96 3.6 57.5 36.3 2.5 4 5 96 3.1 94.2 1.0 1.1 10 6 99 0.8 94.2 2.5 0.9 - - Examples 11-14 The effect of different amounts of CuCl catalyst on the hydrolysis of 4-BPA.

The experiment described in Example 1 was repeated. The modifications are detailed in Table III: Table III Example 15 The hydrolysis of a mixture of 3- and 4-bromophthalic acid Example 1 was repeated with a mixture of 3- and 4-bromophthalic acids (-20:80, respectively). The results were basically the same as those of Example 1, except that the ratio of 3- and 4-hydroxyphthalic acid was practically the same as the starting material, namely ~20:80 respectively, i.e. no isomerisation occured.

Example 16 The effect of various copper compound catalysts on the hydrolysis of 4-bromophthalic acid Example 1 was repeated using various catalysts such as CuSO4-5H2O, CuBr, etc. The results were practically the same as those of Example 1.

Experimental reagents, analytical methods and apparatus Reagents 4-BPA Prepared at IMI 3-HPAn Aldrich 3-HBA Merck CuCl Merck NaOH Frutarom Solvents Commercial A.R. and CP. grade Analytical methods and apparatus The analytical data were determined with the following instruments: Br" analyses were performed by argentometric titration. ' Assay Assay was determined by acid-base titration.

GC/MS Gas-chromatograph: HP 5890A Oven: Initial temperature 70°C, held three minutes and then raised to 240°C at 20°C/min.

Injector: 230°C Detector (transfer line): 250°C Column: Supelco column 2-4086 fused silica, capillary (phase: SBP-20) 30 m x 0.25 mm Split ratio: 1:50 Injection amounts: 1 ml Flow (He): 23 ml/min.

Retention times, min.: PAn - 9.9 3-HPAn - 10.1 3- HBA - 10.8 4- BPAn - 11.5 3- BPA - 12.1 4- HPAn - 13.5 Mass Spectrometer HP 5970 Range: 40-550 a.m.n.

Scan: every 0.9 sec.

NMR spectra Bruker WP 200 MHz H-NMR Solvent: Acetone-dg Scans: 50 Reference: TMS IR spectra FTIR Nicolet 5MX Range: 400-4600 cm*1 Scan: 10 (every 1.0 sec.) Sample: 0.8 mg/80 mg KBr Hvdrolvs-LS apparatus Hydrolyses were carried out in two types of SS-316 autoclaves: 1. Half liter reactor, Parr Instrument Company, Catalog No. 4561. 2. One liter reactor, Autoclave Engineers, Inc.

All the above descriptions and examples have been given for the purpose of illustration and are not intended to constitute a limitation of the invention. Many modifications can be carried out by the skilled chemist without departing from the spirit of the invention. For instance, different alkalis may be used, different reagent ratios, reaction temperatures and catalysts can be employed, all without exceeding the scope of the invention.

Claims (11)

2885/93 112706/2 -11- CLAIMS:

1. A process for the preparation of 4- hydroxyphthalic acid and a mixture of 3- and 4-hydroxyphthalic acids that comprises hydrolyzing the corresponding bromophthalic acids in an aqueous alkaline solution, in the presence of a catalytically effective amount of a copper compound catalyst and in a temperature range of between 100° and 160°C.

2. A process according to claim 1, wherein the hydrolysis is carried out under autogenous pressure.

3. A process according to claim 1 or 2, wherein the alkali in the aqueous solution is selected from among the hydroxides, oxides and carbonates of sodium and potassium, or mixtures thereof.

4. A process according to claim 1, in that the ratio of the alkalis, that are used in aqueous solutions, is an amount of >5 equivalents of the halogen atom in the starting material when bromophthalic acid is used.

5. A process according to claim 1, wherein the catalyst comprises one or more compounds of the formula Cu(n)R(m) wherein: R is -0 , -OH or the anion of an inorganic or organic acid; n is 1 or 2; and m is 0, l or 2.

6. A process according to claim 1, in which copper compound catalysts may be used either individually or in mixtures in an amount of between 2-7% by mole. 2885/93 112706/2 -12-

7. A process according to claim 5, wherein the catalyst is chosen from among Cu, CuCl, CuCl2, CuBr, Cu20, Cu(OH)2, CuS04 and Cu(OAc)2.

8. A process according to any one of claims 1 to 7, wherein the temperatxire range is 100 to 160° C.

9. A process according to any one of claims 1 to 8, wherein the 3- and or 4-bromophthalic acids are converted to 3- and/or 4-hydroxyphthalic acids respectively without isomerisation.

10. A process according to any one of claims 1 to 8, further comprising the dehydration of the corresponding acid to the hydroxyphthalic anhydride.

11. A process according to any one of claims 1 to 10, essentially as described and with reference to the examples. LUZZATTO & LUZZATTO